This invention relates to a dynamoelectric machine, and more particularly, to double radial layered connector ring segments which join stator slot embedded coil sides.
Large dynamoelectric machine designs have evolved which use stator windings of complex shape to handle the voltages and currents required by loads imposed on modern power generation systems. The large number of stator slots, the use of parallel windings in each phase, and multiple loop coils per phase necessitate the use of a complicated end connection scheme for electrically joining stator slot disposed coil sides into a stator winding. Such connection scheme conforms to a restricted space, provides rugged construction, and will also allow necessary connections between the stator coil sides.
The present solution to this problem consists of an end basket made by weaving together diamond-shaped coil sides. Each loop on the multiple coil loop is constructed from two coil sides each of which consists of a straight portion that extends the length of the stator slots and a complicated curved end turn portion at each end thereof. This end turn portion has a complex shape which bends axially, radially, and circumferentially. The manufacturing of the coil sides requires a complex three-dimensional form (typically of wooden construction) against which the copper coil sides are bent and twisted to form the turn portions. The stator coils sides are woven together to form the diamond end basket design for large dynamoelectric machines.
Disclosed in a copending continuation application by D. J. Scott having Ser. No. 57,048, filed on July 12, 1979, and assigned to the assignee of the present application, was a dynamoelectric machine having a stator winding constituting a plurality of coil loops each of which includes two straight coil sides which are embedded in and extend the entire length of the stator slots and protrude into the end regions. Each loop also has a generally C-shaped connector ring segment disposed in a first end region for connecting the two straight sides. The loops are joined in a predetermined manner according to phase by other connector ring segments disposed in the second end region. The connector ring segments are constructed of a material such as roebelled copper strands and hollow copper tubing, for example, and can be either water- or air-cooled.
Although the aforementioned connector ring segments were an improvement over the prior art diamond-shaped coil sides, a copending application by K. R. Davey, having Ser. No. 139,082, filed on Apr. 10, 1980 and having a common assignee with the present application, disclosed an arrangement of interspersing the connector ring segments by phases so as to drastically reduce the operational forces thereon. Further reductions in forces and losses incurred in the end turn regions were obtained from connecting selected top coil sides together and selected bottom coil sides together as disclosed in a copending application by K. R. Davey having Ser. No. 139,081, filed Apr. 10, 1980, and having a common assignee with the present application. In a copending application Ser. No. 57,048, filed on July 12, 1979, a dynamoelectric machine having insulated coil sides arranged in the stator's slots in a circumferentially side-by-side configuration was disclosed. The coil sides in each slot were, according to Scott's disclosure, separated circumferentially from each other by an insulated spacer.
Disclosed herein is a dynamoelectric machine having a stator winding which includes a plurality of multiloop stator coils each loop of which constitutes two straight coil sides which run the entire length of the stator slots and extends into the end regions of the stator. The stator winding also includes a plurality of connector ring segments disposed at each axial end of the stator which electrically connect each pair of coil sides and interconnect the separate loops into coils. The connector ring segments each have a circumferential body portion with a predetermined radius of curvature and a radial arm portion joined to each end thereof. A first group of connector ring segments is characterized by a relatively large radius of curvature and a second group of connector ring segments is characterized by a relatively small radius of curvature. The connector ring segments of the first group are arranged radially outside the connector ring segments of the second group.
The connector ring segments of each group are preferably axially interspersed according to phase to reduce operational forces thereon and losses within. The preferred embodiment of the present invention has radially adjacent connector rings of different phase to further reduce forces thereon. Commonly slotted coil sides arranged in circumferentially adjacent relationship are preferably employed with the previously described double (or more) radial layer connector ring segments. To avoid interference with retaining rings which are typically used on both ends of dynamoelectric machine rotors, the portions of the coil sides which extend into the end regions are directed to a radially outer position relative to the slots and the first and second connector ring groups' radial arms extend outwardly and inwardly, respectively, therefrom. Use of such multiple radial layers of connector ring segments reduces dynamoelectric machine length and copper usage while facilitating field repair of the coils.
Many other advantages and purposes of this invention will be clear from reading the following detailed description of the drawings.